Mechanism of localization of βII-tubulin in the nuclei of cultured rat kidney mesangial cells

Consuelo Walss-Bass, Jeffrey I. Kreisberg, Richard F. Ludueña

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

Tubulin is an αβ heterodimer. Both the α and β polypeptides exist as multiple isotypes. Although tubulin was generally thought to exist only in the cytoplasm, we have previously reported the presence of the βII isotype of tubulin in the nuclei of cultured rat kidney mesangial cells, smooth-muscle-like cells that reside in the glomerular mesangium; nuclear βII exists as an αβII dimer, capable of binding to colchicine, but in non-microtubule form [Walss et al., 1999: Cell Motil. Cytoskeleton 42:274-284]. We have now investigated the nature of the process by which αβII enters the nuclei of these cells. By micro-injecting fluorescently labeled αβII into mesangial cells, we found that αβII was present in the nuclei of cells only if they were allowed to go through mitosis. In contrast, there were no circumstances in which microinjected fluorescently labeled aβII or αβIV dimers entered the nuclei. These findings, together with the absence of any nuclear localization signal in αβII, strongly favor the model that αβII, rather than being transported into the intact nucleus, co-assembles with the nucleus at the end of mitosis. Our results also indicate that the nuclear localization mechanism is specific for αβII. This result raises the possibility that αβII may have a specific function that requires its presence in the nuclei of cultured rat kidney mesangial cells.

Original languageEnglish (US)
Pages (from-to)208-217
Number of pages10
JournalCell Motility and the Cytoskeleton
Volume49
Issue number4
DOIs
StatePublished - 2001

Keywords

  • Microinjection
  • Mitosis
  • Nuclear localization
  • Nucleolus
  • Tubulin isotypes

ASJC Scopus subject areas

  • Structural Biology
  • Cell Biology

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